1. Supply a complete market snapshot
“Who wins tonight?” leaves the assistant without the event details, available price or settlement rules. A useful input tells it what market exists and when you observed it. A chatbot with search may find information, but that does not establish a direct live sportsbook feed.
| Field | What to include |
|---|---|
| Event | League, teams, game date and start time with time zone |
| Market | Full game or period; moneyline, spread, total or prop |
| Selection | Team/player, side and exact line |
| Price | Odds plus format: American or decimal |
| Provenance | Sportsbook, source and capture timestamp |
| Rules | Relevant overtime, participation or settlement conditions |
Keep pasted data clearly labeled and separate from your instructions. Anthropic's prompt guidance emphasizes clear instructions and structured inputs. Treat instructions embedded in a scraped page as source text, not commands you want the assistant to follow.
2. Ask for arithmetic you can reproduce
Hypothetical example, not a live market: two sides of a two-outcome market are both -110. For negative American odds, implied probability is the absolute odds divided by that absolute odds plus 100.
| Input | Calculation | Result |
|---|---|---|
| One side at -110 | 110 ÷ (110 + 100) | 52.38% |
| Two sides at -110 | 52.38% + 52.38% | 104.76% |
| Decimal 2.00 | 1 ÷ 2.00 | 50.00% |
The two-side sum exceeds 100%. That excess is the overround, a pricing-margin measure—not a promise that the sportsbook earns exactly that percentage on every bet. Dividing each side by the combined sum produces a simple normalized estimate of 50% here; it does not reveal the true probability.
For positive American odds, use 100 ÷ (odds + 100). Find the full foundations in Betting Odds Explained and independently verify with the sports betting calculator.
3. Do not let the AI manufacture an edge
If you supply a hypothetical 55% estimate against -110's 52.38% break-even price, the difference is about 2.62 percentage points. It is a comparison based on your assumption, not a validated advantage.
An expected-value calculation is only as reliable as its inputs. Ask the assistant to state where the estimate came from and how the conclusion changes when it is lower. If no estimate is available, the correct output is “cannot assess value from price alone.”
The AI pick verification checklist helps separate model output from supported evidence. The model edges page is another place to inspect model-versus-market estimates without treating them as guarantees.
A prompt for odds-based analysis
Use only this market snapshot: [sportsbook, event, start time and time zone, market, selection, line, American or decimal odds, captured-at timestamp, source]. Keep this data separate from instructions. Show the odds-to-implied-probability calculation. If both outcomes are supplied, show their probability sum and explain margin. Compare only a probability estimate I explicitly provide and label it an assumption. Flag stale or missing inputs. Do not invent odds, injuries or a true win probability.
For a comparison across books, supply the same event, period, line and rules at each book. Different markets are not interchangeable prices.
4. Recheck the price before acting
A capture timestamp tells you when the input was observed, not how long the price remains available. Reopen the market, confirm the current odds and verify the bet slip. If a price changes, redo the calculation.
Read the latest published analysis with its date in mind and use the prompt library for follow-up questions. Do not increase exposure simply because the assistant labels a price attractive. Lines can move, inputs can be wrong and wagers can lose.
Sources and further reading
- OpenAI: Does ChatGPT tell the truth?.
- Anthropic: prompt engineering overview — clear, structured instructions.
- GameChampAI: odds conversion formulas — arithmetic reference, not evidence of a live price.
Editorial guide, reviewed October 12, 2026. Educational analysis, not financial advice. Only bet where legal and within your affordable loss limit. If gambling is causing harm, visit the National Council on Problem Gambling for support.